pH-Mediated Dual-Phase Equilibrium Manipulation and Microstructural Optimization of Y₂O₃-MgO Composites for Enhanced...

Area of Science:

• Materials Science
• Ceramic Engineering
• Nanotechnology

Background:

• Yttrium oxide (Y2O3)-magnesium oxide (MgO) composites are key mid-infrared transparent materials for extreme conditions.
• Microstructural defects like poor phase fractions, grain growth, and inhomogeneity limit their performance.
• Traditional methods fail to control Y3+ and Mg2+ precipitation simultaneously due to solubility differences, causing segregation and poor ceramic quality.

Purpose of the Study:

• To overcome limitations in Y2O3-MgO composite performance by developing a new synthesis strategy.
• To precisely control dual-phase equilibria and microstructure through pH manipulation.
• To achieve atomic-scale precursor homogenization for enhanced ceramic properties.

Main Methods:

• A coprecipitation-solvothermal coupling process was employed with precise pH control (9.31-11.56).
• The Gibbs-Thomson effect was utilized to enhance supersaturation and promote conucleation.
• High pH (≥10.84) was used to ensure complete Mg2+ precipitation and atomic-level precursor homogenization.

Main Results:

• Hot-pressed ceramics exhibited a near-ideal 1:1 phase volume ratio and ultrafine grains (129 ± 4 nm).
• High phase homogeneity (αf > 0.9) was achieved, leading to superior optical and mechanical properties.
• Record transmittance (85% at 6.2 μm, 79% at 7 μm) and an exceptionally broad cutoff window (1.0-11.5 μm) were observed.

Conclusions:

• pH-mediated phase equilibrium control is a universal strategy for designing high-performance oxide composites.
• This method resolves fundamental precipitation mismatches, enabling microstructural optimization in multifunctional ceramics.
• The optimized Y2O3-MgO composites demonstrate enhanced hardness (11.19 GPa) and toughness (2.43 MPa m1/2).